[llvm] [GitHub] Avoid downloading outputs during Bazel tests when possible (PR #224725)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 approved this pull request.

LGTM, seems reasonable enough.

We should also add this to the buildkite pipeline if it's not already there.

https://github.com/llvm/llvm-project/pull/224725